This invention pertains to novel onium surfactants and the precursors thereof.
Surface active agents (surfactants) have been defined as any compound that reduces surface tension when dissolved in water or water solutions, or which reduces interfacial tension between two liquids, or between a liquid and a solid. See "The Condensed Chemical Dictionary," Eighth Edition by G. G. Hawley, Van Nostrand Reinhold Co., N.Y. (1971). Surfactants are useful as detergents, wetting agents and/or emulsifiers and are normally described as being either ionic (cationic or anionic) or nonionic surfactants. The nonionic surfactants are of particular interest in the instant invention.
The nonionic surfactants form a known class of compounds having many members. Those having an end block(s) of polyoxyethylene units terminated with a hydroxyl group (i.e., --CH.sub.2 CH.sub.2 O--.sub.m H) are particularly useful commercially. Such compounds are normally prepared by condensing ethylene oxide (EO) onto a hydrophobic (lipophilic) compound bearing at least one active hydrogen. By "active hydrogen" is meant hydrogen active in the Zerewitinoff reaction. E.g. hydrogen on a carboxyl group, a phenolic hydroxyl group, a mercaptan group, etc. are active hydrogens). The nonionic surfactants are also characterized by their hydrophilic-lipophilic balance (HLB).
The concept of HLB is now widely accepted, particularly for the nonionic surfactants, and is fully described in the literature. See, for example, the text "Emulsions -- Theory and Practice," 2nd. Ed., A.C.S. Monograph No. 162, by Paul Becher, Reinhold Publishing Corp., N.Y. (1965), pp. 232-255.
A wide variety of nonionic surfactants are described in "McCutcheon's Detergents and Emulsifiers -- 1972 Annual," published by McCutcheon's Division, Allured Publishing Corp., N.J. (1972) and in "Nonionic Surfactants," Vol. 1 of the "Surfactant Science Series," edited by M. J. Schiek, published by Marcel Dekker, Inc., N.Y. (1967).
The known class of nonionic surfactants whose members have from 1 to 5 end blocks of polyoxyethylene units terminates with hydroxyl and having an HLB of from 1 to about 30 (preferably from about 5 to about 18) are used herein as reactants leading to the novel onium surfactants. This class of nonionic surfactants is represented by the formula X[(CH.sub.2 CH.sub.2 O--.sub.m H].sub.n, wherein X is an n-valent hydrophobic radical derived by the removal of n-atoms of active hydrogen from an organic compound; m is an integer of at least 1 and is normally from 1 to about 200 and is most frequently from 4 to about 50; and n is an integer of from 1 to 5. The reactants having from 1 to 3 end blocks of polyoxyethylene units (i.e., n is 1, 2 or 3) are currently preferred and those having only one (n is 1) end block of polyoxyethylene units are most preferred. The latter compounds are referred to as monofunctional nonionic surfactants.